Thermo-electric switch.



No. 697,530. Patented Apr. T5, |902.

J. G. NULEN.

THERMO ELECTRIC SWITCH.

(Application filed Sept. 12. 1901.)

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JAMES G. NOLEN, OF CHICAGO, ILLINOIS.

THERMO-ELECTRIC SWITCH.

SPECIFICATIONforming part of Letters Patent No. 697,530, dated April 15, 1902. Application tiled September l2, 1901. Serial No 75,143. (No model To @ZZ whom, t may concern.:

Be it known that I, JAMES G. NOLEN, of Chicago, in the county of Cook and State of Illinois, have invented certainv new and useful Improvements in Thermo-Electric Switches; and I hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which form part of this specilication.

My invention relates to improvements in thermo electric switches. It is especially adapted to b e used in connection with telephone-circuits or in circuits with other instruments wherein it becomes desirable or necessary to automatically open the circuit when been introduced upon the said circuit, the said current being greater than the instruments are intendedto carry.

The object of my invention is to provide a device whereby the circuit will automatically be opened-and may be also grounded by the thermic effect of a current of electricity which is larger than is designed to be carried upon the said circuit.

The primary object o f my invention is to automatically open the circuit containing telephone instruments and incidentally to ground the same by the operation of the device superinduced by the thermiceiect of an overcharge or abnormally large current, which may be introduced upon the circuit from extraneous sources either abruptly or by small successive incrementsuntil the circuit containing the telephone or other instrument becomes overburdened or supercharged to such an extent as to be dangerous, whereupon the thermic effect of the excessive electric current iiowing through the circuit, which has been increased beyond the normal capacity of the said circuit, will cause the liberation ofthe spring switch-blade of the device placed in the said circuit and designed to be liberated thereby, whereupon the circuit containing the said delicate instruments is opened and the circuit over which the excessive current is flowing is diverted to the ground.

In the drawings, Figure 1 is a plan viewof my device. Fig. 2 is a side elevation partly in section. Fig. 3 is an enlarged broken-away detail of one of the stationary terminals. Fig. a is an enlarged broken-away detail of the switch-blades and fuse-support.

In all of the views the same letters and n umerals of reference indicate similar parts.

1 is an insulating-base, upon which mydevice is mounted. The instrument shows a switch for each leg of the telephone-circuit. It desirable, a single switch lnay be used in each circuit and only one leg of the circuit adapted to be thereby opened. I prefer, however, to open both legs of the circuit, especially when a metallic circuit is used.

2 2' and 3 3 are the terminals of the instrument to which the line-wires of the circuit in which it is designed to be employed are connected. The .terminals 3 3 have upwardlyextending spring-clips I 4, and the terminals 2 2 are provided with upwardly-extending angle-pieces 5 5. Studs 6 6, preferably of copper,are insulatedly supported in the anglepieces 5 5 by means of the insulating bushings 7 7, which are made preferably of mica, asbestos, or like material. A small heating-coil S is mounted upon the stud 6 and is connected by one terminal to the anglepiece 5, and the other terminal is connected to the stud 6. The stud 6 projects slightly beyond the front end of the coil 8. The usualv mica-blade fuse-supports 9 9 are capped on their ends by means of metallic clips l() l0 and 11 11. These clips are preferably of copper or similar metal and are joined electrically -by means of a fuse-Wire 12, which is designed to'complete the electric circuit between the clips and 11. The blade 9 is preferably made of an insulating material, such as mica. To the clip 10 of the blade 9 I solder a small piece of metal 13 and allow it to project beyond the end of the clip 10. The soldering material which I use to unite the clip 13 with the clip 10 is adapted to melt at a low degree of temperature. A binding-post 15 is connected to the ground. A stud 16 is connected to the binding-post 15 by means of 95 the wire 17, andv thereby the stud 16 is also connected Vto the ground.

18 18 are the usual static-discharge plates, the lower plate resting upon the ground-strip 19, which is connected to the binding-post 15,

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the upper plate being in contact with the clip 2), which completes the connection to the terminal 3. The plates are separated by the usual insulating material, such as paper, mica, rbc.

The spring-clips L1 1 are inclined inwardly toward a radial'point common to both.

The blade 9, with its accompanying clips 10 and 11 and the fuse 12,is an article of ordinary commerce and may be purchased in the market. After the clip 13 has been soldered to the device the blade 9 is placed in position, one end being inserted in the clip 11, the engaging piece 13 being placed in the position shown in the lower portion of Fig. 1, where the piece 13 is held by the projecting end ofthe stud G. The line-terminals of a telephone-circuit are joined to the terminals 3 3, and the instrument-terminals are joined to the terminals 2 2 of the device. Vhen both of the fuse-supporting blades are in the position shownin the lower portion of Fig. 1, the circuit is com pleted from the terminals 3 through the fusewires 12, the clips 10, the engaging pieces 13, the studs (5, through the coils 8,'through the upright 5 of the terminal 2. This path is of suflicient carrying capacity to accommodate the current that may be necessary in and to the operation of telephone apparatus. Should it happen, however, that a current of greater strength than the telephone instruments and apparatus are able to carry should pass over the circuit in which they are contained, then such surplusfcurrent will suflicientlyheat the coil S to melt the low-fusing solder which joins the engaging piece 13 to the clip 10, when the blade 0 will be liberated. The resilience of the mica blade will cause it to make contact with the stud 16, as shown, and thereby ground the line-terminal and open the circuit communicating with the telephone instruments between the stud G and the clip 10, thus protecting the telephone instrument or such other devices as may be designed to be protected by my device from the effects of an overcharge of electricity. This feature of my device is designed to be brought into action when the current is very gradually increased, known in the art as sneakcurrent,7 to the effect of which the ordinary fusewire is hardly susceptible. Should the current be increased to any abnormal extent suddenly, then the fuse-wire 12 is sufficient to protect, and in that event it would become disintegrated and by that means the circuit would be opened.

My device contains three means for protecting and guarding delicate electrical apparatus--iirst, the ordinary fuse-wire, which is designed to be melted when an excessive current is suddenly introduced upon the circuit; second, the means which I have just describedthat is, the thermo-electric device, whieh is designed to be operated by the gradual increase of the current to an abnornal degree; third, by the static discharge, as

when lightning enters the circuit it will abruptly discharge itself between the plates 13 and the ground through the insulating medium instead of passing through the electric instruments containing self induction and other impeding effects.

The blade i) is the resilient insulating-support, designed to carry the fuse 12, and by the effect of its resiliency it automatically opens the circuit when the fusing metal between the clips 10 and the engaging piece 13 is melted, after which if the extraneous eurrent continues to increase to an abnormal degree the fuse 12 will be melted and the disastrous results of the overeharge ot' current will thereby be entirely averted.

Having described my invention, what I claim as new and useful, and desire to secure by Letters Patent of the United States, is-

1. In a thermo-electric switch the combination with a base of a resilient, insulating fusesupport, a fuse carried thereby, metallic terminals on said support to which said fuse is joined, a means for holding said support under strain and thereby preserving the integrity of the circuit in which said device is placed, and a thermo-electric device adapted to release said fuse-support and thereby open said circuit, substantially as set forth.

2. In a thermo-electric switch the combination with a base of a mica blade provided with metallic terminals, a fuse-link connected to said terminals, a spring-clip for supporting one end of said mica blade, an engaging piece soldered to the metallic terminal of the other end of said mica blade, a stud adapted to be heated by a current of electricity, a coil surn rounding said stud and in circuit with said fuse-link, the arrangement being such that said mica blade is under tension when said engaging piece is in contact with said stud, and will be moved away from said stud when the solder joining said engaging piece with said fuse-terminal has been melted, substantially as set forth.

3. In a thermo-electric switch the combination with a base of a resilient, insulating fusesupport, a fuse carried thereby, metallic terminals on said support to which said fuse is joined, a spring-clip for holding one end of the said support, a stop-piece soldered to the other end of said support, a Afixed electric terminal against which said stop is adapted to bear, and a means for heating said terminal and melting the solder between said stop and said support,whereby the support is displaced by virtue of its inherent resilience, and the circuit thereby opened, substantially as set forth.

Li. In a thermo-electric switch the combination with the base 1 of a clip fi of an insulating spring-blade fuse-support having a fuse 12 and terminals 10 and 11 joined thereto, a removable stop 13 soldered to the terminal 10, a fixed electrical terminal G against which IOO IIO

said stop is adapted to rest and a heatingmy own I ax my signature in presence of coil S adapted to heat the terminal 6 and the two Witnesses. stop 13 so as to melt the solder that holds the stop 13 to the clip 10 when an'abnormal 3 current is owing over the coil S, substan- In presence oft-ially as sot forth. FORE BAIN, In testimony that I claim the foregoing as M. F. ALLEN.

JAMES G. NOLEN. 

